1. Field of the Invention
This invention relates to cabs and sleepers for trucks.
2. Description of the Related Art
Road transport trucks intended to carry loads long distances often are provided with sleepers mounted behind the cabs of the trucks. The driver operates the truck while sitting in the cab. The driver may park the truck at a truck stop or rest station, and then rest inside the sleeper behind the cab. Alternatively, one driver can sleep in the sleeper while another driver drives the truck. For this reason, the sleeper is generally accessible from the cab.
The sleeper typically has the shape of a generally rectangular parallelepiped and contains a compartment which is usually provided with a bed so that the driver may enjoy comfortable sleep. The sleeper may also contain a closet, a desk, shelving and other furniture, storage containers, and appliances useful in long distance travel. The cab and the sleeper of a transport truck are usually mounted above the frame of the truck on suspension apparatus in order to permit a more comfortable ride for the driver(s). The sleeper may be an extension of the cab or may be a separate unit mounted behind the cab.
Transport trucks are usually supplied according to the specifications of the owner. Thus, the owner may specify whether or not the truck will have a sleeper, the size and furnishings of the sleeper if one is required, in addition to a myriad of other specifications for the truck. An example of a line of trucks which may be custom built to the specifications of the owner is the Western Star Constellation series of trucks. A company manufacturing such trucks, however, must be able to provide cabs and sleepers of different sizes and heights. Such companies, therefore, must be able to readily manufacture cabs and sleepers of different specifications according to the demands of the market. A reduction in the expense and difficulty of manufacturing cabs and sleepers is desirable.
Cabs and sleepers add to the weight of a truck. Reducing the weight added by the cab and sleeper is desirable because a transport truck faces overall weight restrictions imposed by highway regulations. The weight saved in the cab and/or sleeper can be added to the payload.
Hitherto, cabs and sleepers usually have been made of sheet steel in a manner well known to the automotive art. U.S. Pat. No. 5,560,673 to Angelo and U.S. Pat. No. 5,310,239 to Koske et al. disclose cabs and sleepers of this type of manufacture.
Sheet steel is heavy. In addition, large flat or curved surfaces of sheet steel must be reinforced by internal ribbing and struts adhered or tack welded to the external sheet in order to preserve the shape and rigidity of the sheet. The additional struts or bracing add further to the weight of cabs and sleepers made this way. In addition, the contacts between the struts and the external sheet of steel create stress points which affect the smoothness of the external surface of such a sheet, which detracts from the external appearance. Sleepers especially have large flat or curved surfaces and manufacturers have found it difficult to make these surfaces smooth and free of stress points because of the inherent limitations of the sheet steel technology. Sheet steel construction also results in problems with vibration. Insulation is generally provided to dampen vibration and protect against external temperature extremes.
U.S. Pat. No. 5,083,834 to Moffat et al. disclosed a sleeper made as a one-piece box-type shell composed of fiberglass reinforced plastic materials. Such a construction is claimed to be lighter, better insulated, less costly and better looking. A one piece construction of this type, however, is not readily altered or repaired.
Accordingly, a need exists for lightweight cabs and sleepers for transport trucks. The sleepers especially should be readily manufactured in a number of different sizes and models in order to accommodate the demands of the market. The sleepers should be readily attachable to a cab and provide easy access between the cab and the sleeper. Such sleepers should be strong and provide vibration and temperature insulation. Preferably, the external surfaces of such sleepers should be smooth for an attractive appearance.